From BBC News:
Celia Sanchez was at the heart of the Cuban revolution for over two decades and after meeting Fidel Castro in 1957, she became his indispensable aide.
There has been speculation they were lovers. But neither Sanchez when she was alive, nor Castro, ever addressed the rumours. Outside Cuba, little has been written about the role Celia Sanchez played until her death in 1980.
The earliest picture of Sanchez and Castro together was taken when they first met, in 1957, but Sanchez had already played a crucial part in his life.
When Castro came to power in 1959, Sanchez remained his most valuable aide, and worked alongside him until her death.
She was in charge of numerous revolutionary projects. From overseeing the "re-education" of the families of anti-Castro insurgents, to founding parks and ensuring Cubans had ice-cream, Celia was the go-to woman.